Extension causes Firefox to not restore window locations on startup

[rk-exxec]

Hey,

I installed your extension and it works as advertised, however since then, Firefox does not remember the window locations on startup.

I have 2 screens and 2 windows for Firefox, on each screen one.
Without your extension enabled, Firefox restores the windows to their respective screens.
If I enable the extension, all windows open on the primary screen.

System: Windows 10, Firefox latest stable (108)